Apparatus for controlling fuel supply to furnaces and the like



y 1942 D. w. FEHRENBACH 2,283,496

APPARATUS FOR CONTROLLING FUELSUPPLY TO FURNACES AND THE LIKE Filed July 31, 1939 11V VEN TOR 0051a 14 fave/wa A TTORNE Y Patented May 19, 1942 UNITED STATES PATENT OFFICE.

APPARATUS FOR CONTROLLING FUEL SUP- PLYTO FURNACES AND THE LIKE Daniel w. Fehrenbach, Kansas "city, 110., assignor to Kansas City Journal-Post Company, Kansas City, Mo., a corporation of liflssouri Application July 31, 1939, Serial No. 281,470

' a Claims. (c1. 1523-28). This invention relates to an apparatus for controlling the fuel supply to a furnace or like appliance particularly operating on liquid or gaseous fuels.

In furnaces of this type the flame, for various reasons.-often becomes extinguished with the result the fuel continues to flow and soon fills the combustion chamberwith a highly explosive mixture that may cause a serious explosion. Besides the explosive hazard in the combustion chamber the fuel is wasted, and in the case of liquid fuels,

of the furnace.

tice. Located the front wall ofthe furnace is the usual fire-door 9 through which-access is had to the burner for inspection and lighting purposes.

The construction thus far described is cor ventional to fuel burning apparatus of this char-' the fire hazard is extended beyond the confines It is, therefore, the principal object of the motely indicate functioning thereof.

In accomplishing these and other objects of the invention, I have provided improved details supply should the flame of structure, the preferred form of which is il-- lustrated in the accompanying drawing, wherein:

Fig. l is a perspective view of a portion of a furnace equipped with a control apparatus embodying the features of the present invention, parts of the furnace being broken away to better illustrate mounting of the photoelectric cell with respect to the burner, and the door switch for automatically establishing fuel supply when the door is opened to light the burner.

Fig. 2 is a wiring diagram of the control apparatus.

Referring more in detail to the drawing:

I designates a conventional furnace having a combustion chamber 2 equipped with a burner 8 adapted for burning a liquid or gaseous'fuel. The burner 3 is mounted within an opening 4 in the front wall of the furnace and is supplied with fuel through a pipe line 5 having a manually operated valve 6 and a magnetically operated valve 1 connected therein. In case of a liquid fuel such as heavy oils. the burner is provided with a steam connection 8 for effecting vaporization of the fuel, as in conventional pracacter and specifically forms no part of the present invention which provides means for automatically interrupting the fuel supply in case the flame indicated at It should'become extinguished.

In carrying out the present invention the net valve I includes a valve body I I, having a fuel inlet and outlet. l2 and I3 'interconnectedfby a valve port l4. The valve port constitutes a seat for a valve ii that is normally seated by ravity to close flow through the line 5. The valve It includes a stem 16 having operable connection with a solenoid coil I! which isjadapted to be supplied with an energizing current from service line wires l8,and l9 throughconductors 20 and 2|. The conductor 2| is directly connected with one of the terminals of the solenoid through interconnecting wires 22 and .23, but

the other conductor 20 is connected by wires 24 and 25 with a switch 26, which in turn is connected with the'other lead of the solenoid winding by a conductor 21. The circuit through the conductors 20 and 2i is manually operated by a main switch 28 that is mounted on a switch I panel29.

The switch 26 is located adjacent the firedoor 9 and has a plunger 30 arranged to be engaged by the fire-door. When the door is closed the circuit is open, and when the door is open the circuit is closed, as later described. I

Also connected in the circuit parallel with the switch 28 is a delay or timing switch 3| including a pivoted lever 32 carrying a, contact '33 adapted to bridge contacts 34 and 35 that are connected with the wires 25 and 21 by wires 38 and 31 respectively. The lever is moved to circuit closing position by a spring 38 and away from circuit closing position by a time actuated trip mechanism 39.

ment 40 pivotally mounted as. at 4| on a lever 42 which has a fixed pivot 43. The teeth on the segment 40 are retained in engagement with the The trip mechanism includes a gearseg t -permit access to the burner. opening of the door 9, the switch 26 automati- .l-callycloses so that a current flowsthrough the conductors 21,22 and- 23 .to the magnet l1, cong;ductor 21, switch 26, conductors 25, 24 and 20.

directed into the combustion chamber and exposed to the light of the flame when in propagation, whereupon a circuit is established from the photoelectric cell through conductors 50 and to an amplifying tube 52 that is located within a housing 53 on the switchboard to generate an amplified current in the plate circuit thereof which acts through conductors 54 and 55 to energize an electromagnet 56 which operates a switch 56'.

The switch 56' includes an armature 51, have ing connection by a conductor 58 with the conductor 2| previously described. .The switch also includes spaced contacts 59 and 60' adapted to be alternately engaged bythe armature. The armature is normally retained in circuit closing position with the contact 59.by a spring 6|, and upon energization' of the electromagnet 56, the armature is moved into engagement with the contact 60 to close circuit throu h the magnet 48 by way of a wire 62 that is connected with one of the leads of the electromagnet 48. The other lead of the electromagnet 55 is connected by a conductor 63 with the wires 24 and 25. Thus when the electromagnet 56is energized the magnet 48 is also energized through the armature and switch contact 60, raising the segment 40 .to allow closing of the contacts 34 and 3-5 and establish, a second circuit through the magnet l'l of the valve fl, whereby the valve is retained in open position when the door is reclosed'and aslong as a flame is burning in the combustion amber. In case the flame should become exthe photoelectric cell thereby interrupting the plate Qcircuit -so' that the magnet 561s deenergized v and ythe spring 6| is free to break circuit cr me-armature 51 with the contact to.

riguishe'd the current ceases to flow throughv The circuit to the magnet 48-is controlled by and actuated by an electromagnet 65 having" arelay: switch -64 located in the conductor '62 through wires 66 and 61.1respectively.

I The timing switch 3|; including the actuating mechanism therefor and relay switch 64 aremounted within a suitable housing 68'on the t panel 29; as shown in Fig. 1.

1 In order'to visibly indicate when the fuel is cut oil to the burner, the contact 59 is connected by a conductor 69 with a preferably red signal light 10 through which circuit'is completed by a wire H. A similar signal light 12 ofdifferent color may be connected with the conductor 24 by a wire 13 andwith the conductor -62 by a wire 14, which light is energized'when current is fiowing through the magnet -of the delayed action switch 3|, thereby-indicating that the burner is 'inoperation. Another signal 15 of still different color may be connected to the conductors 23 and 31 'byrwir'es 'lliand Tl respectively to indicate whenthe magnet actuated valve 1 is opened.

"dicate the circuit is closed and that the burner isnot operating. The fire-door 9 is then opened Incidental to to the line conductor l8, thereby energizing the connection with the conductors 21 and 23 magnet and effecting opening of the fuel valve I so that the burner may be lighted upon opening of the hand valve 6. At the time of opening of the valve 1, a current flows through the signal light 15 to show that the fuelvalve is opened.

After the burner is lighted and the flame is in operation, the light of the flame causes a current to be generated by the photoelectric cell, .which current flowing through wires Ell-5| to the amplifying tube effects energization of the plate circuit thereof and causes the magnet to move the armature 51 into engagement with the contact 60. When the magnet 56 is-energized the circuit to the signal 10 is broken and currentis established through the relay switch 64. Simultaneously with energization of the magnet winding H, the magnet 65 is also energized through the conductors66 and 61 to close the switch 64. Current is now flowing through the conductors 2i, armaturev 51, contacts 60, conductor 62, switch 64, magnet winding 48, conductor 24 and conductor 20 to'the line l8, thereby energizing the magnet 46 toeifect release oi the lever 32 so that the spring 38 closes the contacts. 34 and 35. When the fire-door is. closed the switch 26 .is,- of course, opened, but circuit is maintained through the valve coil l1 incidental to closing of the contacts 34 and 35. As long as the magnet 48 is in circuit, the signal light 12 will be energized'indicating that the burner is in operation. The signal 15 will also be energized 'indicating that the fuel valve is open.

Now, assuming that for some reason the flame of the burner should become extinguished, when this occurs current ceases toflow through the photoelectric cell controlled relay portion of the circuit with the result that current is ,broken through the coil 56. The spring 6| then comes into play to move the armature into engagement with the contact 59 energizing the signal 16 to indicate that the burner .is out of operation.

Upon breaking of the contact current is again interrupted to the magnet 43, whereupon the armature is adapted to drop by gravity to again movethe gear segment, under control of the escapement, into engagement with the lever 32 so that the contacts 34 and .35are broken. Upon breaking of the contacts 34 and 35 current is interrupted to the magnet I1 of thefuel control valve 1 and the valve is caused to seat, shutting oif the fuel supply, Simultaneously circuit is broken in the magnet winding to eifect opening of the switch 64.

Downward movement of the armature 4'! is controlled by the escapement so that opening of the contacts 34 and 35 is delayed. This is an important feature for the reason that the flame may momentarily smoke or flicker so that the photoelectric cell would tend to break circuit to the fuel valve, but if the smoke or flickering clears up before the armature 41 has reached the bottom of its stroke, the contacts 34 and 35 remain closed and maintain the fuel valve open since the cell is still responsive to the light of the flame, and after the difilculty has cleared the current through the magnet 48 which has momentarily interrupted, is again effective to return the armature and segment to their original positions. However, if the fire continues to flicker, the segment 40 will have reached its" lowermost positionto engage the lever 32 which causes opening of the contacts 34 and 35. Opening of these contacts breaks'circuit to the valve magnet l1, and the valve seats to stop flow of fuel to the burner and thereby shut down operation of the furnace. It is then necessary for the operator to relight the burner as above described, and unless the burner is adjusted so that it will operate efficiently, the smoking and flickering condition will again cause closureof the fuel valve.

From the foregoing it is obvious that I haveprovided a simple and efiicient control mechanism for automatically operating the fuel valve to establish fuel supply to a burner and which, as long as the flame is being propagated, will retain the fuel valve open and continue operation of the burner.

a source of electric current, a switch having connectionwith said fire-door for closing said circuit when the fire-door is open, a photoelectric cell supported in the light zone of a flame from said burner, a normally opened switch insaid electromagnetic valve circuit, an electromagnet for effecting closure of the normally open switch, and a relay circuit connected with said electromagnet and with the photoelectric cell for energizing the electromagnet to effect-closure of said normally open switch when the photoelectric cell is activated by the flame from said burner to maintain the electromagnetic valve circuit in operation after opening of said door switch upon closure of the fire-door.

2. An apparatus of the character described including, a furnace having a fire-door, a burner, a source of fuel supply connected with the burner, an electromagnetic valve controlling said fuel supply to the burner, an electric circuit connected with the electromagnetic valve, a source of current supply for said circuit, a switch having connection with said fire-door for closing'said circuit when the fire-door is open, a photoelectric cell supported in the light zone of a flame issuing from said burner, a normally open switch in said electromagnetic valve circuit, an electromagnet for effecting closure of the switch, a relay circuit connected with said lectromagnet and with the photoelectric cell for energizing the electromagnet to effect closure of said switch when the photoelectric cell is activated by the flame from said burner to maintain the electromagnetic valve circuit in operation after opensaid circuit when the fire-door is open, a photoelectric cell supported in the light zone of a flame issuing from said burner, a normally open switch in said electromagnetic valve circuit, an electrolay circuit connected with said electromagnet and with the photoelectric cell for energizing the electromagnet to effect closure of said switchv when the photoelectric cell is activated by the flame from said burner to maintain the electromagnetic valve circuit in operation after opening of said door switch upon closure'of the firedoor, and timing means havingoperative connection with theelectromagnet to effect delay in opening of the electromagnetic valve circuit upon interruption of said relay circuit.

4. An apparatus of the character described in- :cluding, a furnace having a fire-door, a burner,

a fuel supply line connected with the burner, an electromagnetic valve in said supply line, a circuit connected with the electromagnetic valve, a switch having connection with said fire-door for closing said circuit when 'the fire-door is open, a photoelectric cell supported in the light zone of a flame issuingfrom said burner, a normally open switch in said electromagnetic valve circuit, an

electromagnet for effecting closure of theswitch, a relay circuit connected with,said electromagnet and with the photoelectric cell for energizing the electromagnet to effect closure of. said switch when the photoelectric cell is activated by the flame fromsaid burner to maintain the electromagnetic valve circuit in'operation after opening of said door switch upon closure of themedoor, an electromagnetic switch .in the photoelectric cell relay circuit and having connection with the electromagnetic valve circuit whereby the photoelectric relay circuit is closed. upon energization of the electromagnetic valve, and timing means having operative connection with the electromagnet to effect delay. in opening of the electromagnetic valve circuit.

5. An apparatus of the character described including, a furnace having a fire-door, a burner, a fuel supply pipe connected with the burner, an

electromagnetic valve in said fuel supply pipe,

a circuit connected with the electromagnetic valve, a source of electric current, a switch having connection with said fire-door for closing said circuit when the fire-door is open, a photoelectric cell supported in the light zone of a flame from saidburner, a normally open switch in said electromagnetic valve circuit, an electromagnet for effecting closure of the normally open switch, a relay circuit connected with said electromagnet and with the photoelectric cell for energizing the eleotromagnet to effect closure of said normally open switch when the photoelectric cell is activated by the flame from said burner to maintain the electromagnetic valve circuit in operation after opening of said door switch upon closure of the fire-door, and signals connected in said circuits for remotely indicating operating condition of the burner.

6.- An apparatus of the character described including, a furnace having a fire-door, a burner, a fuel supply line connected with the burner,a control valve in said line, means having connection with the fire-door and with the control valve for effecting opening of the control valve upon opening the fire-door, means supported in the light zone of a flame issuing from said sive to the light of said flame, and means for delaying closure of'said valve.

DANIEL W. FEHRENBACH.

' magnet for effecting closure of the switch, a re- 

